Production of artificial materials



Patented Nov. 14, 1939 UNITED STATES PATENT OFFICE PRODUCTION OF ARTIFICIAL MATERIALS No Drawing. Application January 3, 1930, Se-

rial No. 418,414. In Great Britain January 18,

3 Claims.

This invention is a continuation in part of our United States application S. No. 402,785, filed October 26, 1929 now Patent No. 2,147,640, corresponding to British application No. 32,284/28, and relates to the production of filaments, threads, ribbons, films and other products by wet spinning processes from solutions of cellulose derivatives, for example cellulose acetate, formate, propionate, butyrate or other carboxylic acid esters or other esters of cellulose, or methyl, ethyl or benzyl cellulose or other cellulose ethers.

In the said United States application S. No. 402,785, filed October 26, 1929 now Patent No. 2,147,640, wet spinning processes are described for the production of filaments, films or other products in which the coagulation is effected under such conditions that the products are, after coagulation, in a plastic condition, that is to say in a condition in which they do not exhibit elasticity, or alternatively after coagulation the products are brought to such a state. The said application describes three methods for the production of filaments, threads or the like, namely (1) by incorporating in the spinning solution solvents or strong swelling agents of higher boiling point than the non-solvent medium to be employed for coagulation, (2) by incorporating suitable solvents or swelling agents in the coagulating medium itself, (3) by treating the filaments, threads or other products after coagulation with a medium containing the solvent or strong swelling agent.

We have now found that very useful results may be obtained by using as a coagulating agent and/or as a subsequent treating agent one or more substances which though swelling agents for the cellulose derivatives are nevertheless not solvents therefor, and in consequence are capable of coagulating the cellulose derivative from its solution. Such agents are for example, non-solvent plasticizing agents, such as the tri-aryl phosphates, for instance tri-cresyl phosphates, alkyl phthalates, e. g., di-ethyl phthalate, and the aryl sulphonamides or their alkyl or aryl dervatives, e. g., the mono methylated or ethylated isomeric xylene sulphonamides.

If the non-solvent swelling agent constitutes the whole of the coagulating medium or medium used for subsequent treatment, it must be liquid, and in such cases swelling agents which are normally liquid may be employed, or two or more of such agents, the mixture of which is liquid, may be employed together.

Preferably the tri-aryl phosphate, alkyl phthalate or other swelling agent is employed diluted with a solvent for the cellulose derivative, and it is found that particulary valuable results are obtained by using acetone in admixture with triaryl phosphates, alkyl phthalates or like swelling agents. Alternatively or in addition the swelling agent may be diluted with a liquid which is a non-solvent for the cellulose derivative. In such cases of employing swelling agents in conjunction with solvents or non-solvents it is not of course essential that the swelling agent shall itself be liquid so long as its mixture with the other constituent or constituents is liquid. Preferably the swelling agent is employed in a high proportion in such mixtures, for example a proportion of to 90% of the whole medium.

It will be seen that the present invention consists essentially in substituting swelling agents which are non-solvents for the cellulose derivatives for the solvents or strong swelling agents in the coagulating baths or in the subsequent treatment baths of the said United States application No. 402,785, filed October 26, 1929 now Patent No. 2,147,640, and reference is made to the said application for details as to methods of effecting the actual spinning or coagulation.

The following examples illustrate the invention but are not intended to limit it in any way.

Eaample 1 A 26% solution of cellulose acetate in acetone is extruded into a bath consisting of tricresyl phosphate and 30% acetone, the formed filaments or the like being carried over or round a feed roller run at a peripheral speed of 30 metres per minute. The filaments or the like from the roller are led continuously into a centrifugal box. After evaporation of the volatile solvent the tri-cresyl phosphate is extracted from the yarn with the aid of benzene leaving a whitish thread of subdued lustre.

Example 2 A 26% solution of cellulose acetate in acetone is extruded into a bath consisting of di-ethyl phthalate and 10% acetone, the formed filaments or the like being carried over or round a feed roller run at a peripheral speed of 25 metres per minute, and being led continuously into a centrifugal box or on to a bobbin. After evaporation of the volatile solvent the di-ethyl phthalate may if desired be extracted from the yarn by means of any suitable solvents.

What we claim and desire to secure by Letters Patent is:

1. In a process for the manufacture of artificial materials by processes wherein spinning solutions containing organic derivatives of cellulose are treated with liquid coagulating media, the step of subjecting said materials after coagulation to the action of a liquid containing at least 50% of non-solvent plasticizing agents for the cellulose derivatives.

2. In a process for the manufacture of artificial filaments and threads by processes wherein spinning solutions containing organic derivatives of cellulose are extruded into liquid coagulating media, the step of subjecting said materials after coagulation to the action of baths which are wholly organic in nature and contain at least 60% of non-solvent plasticizing agents for the cellulose derivatives.

3. In a process for the manufacture of artificial materials by processes wherein spinning solutions containing organic derivatives of cellulose are treated with liquid coagulating media, the steps of subjecting said materials after coagulation to the action of baths containing at least 50% of non-solvent plasticizing agents for the cellulose derivatives and subjecting the treated materials to a stretching operation.

WILLIAM ALEXANDER DICKIE. PERCY FREDERICK COMBE SOWTER. 

